违反多重性约束。关系“ Repository.Person_Projects”的角色“ Person_Projects_Source”具有多重性1或0..1 [英] Multiplicity constraint violated. The role 'Person_Projects_Source' of the relationship 'Repository.Person_Projects' has multiplicity 1 or 0..1
问题描述
您好,在使用其他数据类型之前遇到了此问题。有关更多详细信息,请参见此处。
违反多重性约束的实体框架5
Hello had this problem before with another data type. For more details you can see here. Multiplicity constraint violated Entity framework 5
但是现在该解决方案不起作用或网上找不到其他解决方案。
But now that solution doesn't work or any other found on the net.
我的课程是:
namespace Prometheus.Models
{
[Table("People")]
public class Person : IPerson, INamedEntity
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public virtual int Id { get; set; }
[DisplayName("Prenume")]
public virtual string FirstName { get; set; }
[DisplayName("Nume")]
public virtual string LastName { get; set; }
public string Name
{
get
{
return FirstName + " " + LastName;
}
set { }
}
[DisplayName("Email")]
public virtual string Email { get; set; }
public DateTime? LastModified { get; set; }
public virtual ICollection<Result> Results { get; set; }
public virtual ICollection<Project> Projects { get; set; }
}
}
和
public class Project :INamedEntity
{
public int Id { get; set; }
public DateTime? LastModified { get; set; }
[DisplayName("Titlu Proiect")]
[Required]
public string Name { get; set; }//Title
[Required]
[DisplayName("Tip proiect")]
public virtual ProjectType ProjectType{ get; set; }
[DisplayName("Status proiect")]
public virtual ProjectStatus ProjectStatus { get; set; }
[Required]
[DisplayName("Tip program")]
public virtual ProgramType ProgramType { get; set; }
[Required]
[DisplayName("Numar luni")]
public int NumberOfMonths { get; set; }
[Required]
[DisplayName("Project title")]
public string NameEn { get; set; }
[Required]
[DisplayName("Acronim")]
public string Acronym { get; set; }
[Required]
[DisplayName("Numar contract")]
public string ContractNo { get; set; }
[Required]
[DisplayName("Domeniu de activitate")]
public virtual ActivityField ActivityField {get;set;}
[Required]
[DisplayName("Summary")]
public string SummaryEn { get; set; }
[Required]
[DisplayName("Rezumat")]
public string SumarryRo { get; set; }
[Required]
[DisplayName("Data inceput")]
public virtual DateTime StartDate { get; set; }
[Required]
[DisplayName("Data sfarsit")]
public virtual DateTime EndDate { get; set; }
[Required]
[DisplayName("Institutie coordonatoare")]
public virtual string CoordInstitution { get; set; }
[DisplayName("Valoare totala proiect")]
public decimal TotalValue { get; set; }
[DisplayName("Valuta")]
public virtual Currency Currency { get; set; }
[DisplayName("Rol in proiect")]
public virtual RoleInProject RoleInProject { get; set; }//coord proiect/partener/in afara inst
[DisplayName("Echipa proiect")]
public virtual ICollection<Person> People { get; set; }
[DisplayName("Director proiect")]
public virtual Person ProjectManager { get; set; }
public virtual ICollection<Institution> Partners { get;set;}
public virtual Person PersonInCharge { get; set; }
[DisplayName("Functie/Rol Expert In Proiect")]
public string UserFunctionInProject { get; set; }
[DisplayName("Pagina proiectului")]
[Required]
public string Website {get;set;}
public virtual ICollection<Result> Results { get; set; }
}
当我遇到之前的问题时,它是与Result类相同的人员并被告知,如果我要建立多对多关系,则必须向人员添加一个集合,向结果添加一个集合,然后就可以了。
When i had the previous problem it was with a class Result and the same Person and was told that if i want a many-to-many relationship i have to add a Collection to Person and a Collection to Result and that did the trick.
但是现在,如您所见,我已经拥有
But now as you can see i already have
public virtual ICollection<Person> People { get; set; } in Project
和
public virtual ICollection<Project> Projects { get; set; } in Person
每次我尝试向项目中添加多个用户时,我都会收到错误消息从 DbContext
And every time i try to add more than one User to the project i get the error in that title when calling the Save()
method from DbContext
我不知道该怎么办。
谢谢。
I have no idea what to do. Thanks.
偶然发布了错误的类,它是结果而不是Person,现在是正确的
Accidentally posted the wrong class, it was the result instead of the Person, now it's correct
更新1
public void AddProjectForUsers(IEnumerable<int> userIds, Project project)
{
foreach (var id in userIds)
{
AddProjectForUser(id,project);
}
}
public void AddProjectForUser(int userId, Project project)
{
var user = _ctx.Users.SingleOrDefault(u => u.Id == userId);
if (user != null)
{
if (!user.Projects.Contains(project))
{
user.Projects.Add(project);
}
}
}
public bool Save()
{
return _ctx.SaveChanges() > 0; // the error is thrown here
}
这3个来自我的存储库类
The 3 are from my repository class
对他们的呼叫是
Repo.AddProjectForUsers(team, project);
Repo.Save();
团队是 IEnumerable< int>
并且项目的类型为 Project
Where team is an IEnumerable<int>
and project is of type Project
推荐答案
似乎您可能需要 InverseProperty
数据注释属性可以做到这一点:
It looks like you may need the InverseProperty
data annotation attribute to do this:
namespace Prometheus.Models
{
[Table("People")]
public class Person : IPerson, INamedEntity
{
...
[InverseProperty("People")]
public virtual ICollection<Project> Projects { get; set; }
}
}
public class Project :INamedEntity
{
...
[DisplayName("Echipa proiect")]
[InverseProperty("Projects")]
public virtual ICollection<Person> People { get; set; }
}
您收到的异常消息很能说明问题。由于EF抱怨该关系应该是一对零或一的关系,因此使我相信EF混淆了People-Projects关联与PersonInCharge-Project或ProjectManager-Project关联。
The exception message you are receiving is very telling. Since EF is complaining that the relation is expected to be a one-to-zero-or-one, this leads me to believe that EF is confusing the People - Projects association with either the PersonInCharge - Project or ProjectManager - Project association.
解决此问题的一种方法是在您的Project实体上公开外键属性,无论如何,您都应该这样做-如果不这样做,则会出现奇怪的瞬时错误。另一种方法是使用流畅的API(又称模型构建器)代替数据注释。
One way to solve this would be to expose foreign key properties on your Project entity, which you should be doing anyway - you can get weird transient errors when you don't. Another way would be to use the fluent API (a.k.a. model builder) instead of data annotations.
这篇关于违反多重性约束。关系“ Repository.Person_Projects”的角色“ Person_Projects_Source”具有多重性1或0..1的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!